<template>
  <view class="easy-loadimage" :id="uid">
    <image class="origin-img" :src="imageSrc" mode="widthFix"> </image>
  </view>
</template>
<script>
import { throttle } from '@/libs/uniApi'
// 生成全局唯一id
function generateUUID() {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
    let r = (Math.random() * 16) | 0,
      v = c == 'x' ? r : (r & 0x3) | 0x8
    return v.toString(16)
  })
}
export default {
  props: {
    imageSrc: {
      type: String,
    },
    image: {
      type: String,
    },
    mode: {
      type: String,
    },
    loadingMode: {
      type: String,
      default: 'looming-gray',
    },
    openTransition: {
      type: Boolean,
      default: true,
    },
    viewHeight: {
      type: Number,
      default() {
        return uni.getSystemInfoSync().windowHeight
      },
    },
  },
  data() {
    const that = this
    return {
      uid: 'uid-' + generateUUID(),
      loadImg: false,
      showImg: false,
      isLoadError: false,
      borderLoaded: 0,
      showTransition: false,
      scrollFn: throttle(function () {
        // 加载img时才执行滚动监听判断是否可加载
        if (that.loadImg || that.isLoadError) return
        const id = that.uid
        const query = uni.createSelectorQuery().in(that)
        query
          .select('#' + id)
          .boundingClientRect((data) => {
            if (!data) return
            if (data.top - that.viewHeight < 0) {
              that.loadImg = !!that.imageSrc
              that.isLoadError = !that.loadImg
            }
          })
          .exec()
      }, 200),
    }
  },
  methods: {
    init() {
      this.$nextTick(this.onScroll)
    },
    handleBorderLoad() {
      this.borderLoaded = 1
    },
    handleBorderError() {
      this.borderLoaded = 2
    },
    handleImgLoad(e) {
      this.showImg = true
      setTimeout(() => {
        this.showTransition = true
      }, 50)
    },
    handleImgError(e) {
      this.isLoadError = true
    },
    onScroll() {
      this.scrollFn()
    },
  },
  mounted() {
    this.init()
    uni.$on('scroll', this.scrollFn)
    this.onScroll()
  },
  // eslint-disable-next-line vue/no-deprecated-destroyed-lifecycle
  beforeDestroy() {
    uni.$off('scroll', this.scrollFn)
  },
}
</script>

<style scoped>
/* 官方优化图片tips */
image {
  will-change: transform;
}
/* 渐变过渡效果处理 */
image.origin-img {
  width: 100%;
  height: 100%;
  /* opacity: 0.3; */
  max-height: 360rpx;
}
image.origin-img.show-transition {
  transition: opacity 0.5s;
  opacity: 1;
}
image.origin-img.no-transition {
  opacity: 1;
}
/* 加载失败、加载中的占位图样式控制 */
.loadfail-img {
  height: 100%;
  /* background: url('~@/static/easy-loadimage/loadfail.png') no-repeat center; */
  background-size: 50%;
}
.loading-img {
  height: 100%;
}
/* 转圈 */
.spin-circle {
  /* background: url('~@/static/easy-loadimage/loading.gif') no-repeat center; */
  background-size: 60%;
}
/* 动态灰色若隐若现 */
.looming-gray {
  animation: looming-gray 1s infinite linear;
  background-color: #e3e3e3;
}
@keyframes looming-gray {
  0% {
    background-color: #e3e3e3aa;
  }
  50% {
    background-color: #e3e3e3;
  }
  100% {
    background-color: #e3e3e3aa;
  }
}
/* 骨架屏1 */
.skeleton-1 {
  background-color: #e3e3e3;
  background-image: linear-gradient(
    100deg,
    rgba(255, 255, 255, 0),
    rgba(255, 255, 255, 0.2) 50%,
    rgba(255, 255, 255, 0) 80%
  );
  background-size: 100rpx 100%;
  background-repeat: repeat-y;
  background-position: 0 0;
  animation: skeleton-1 0.6s infinite;
}
@keyframes skeleton-1 {
  to {
    background-position: 200% 0;
  }
}
/* 骨架屏2 */
.skeleton-2 {
  background-image: linear-gradient(-90deg, #fefefe 0%, #e6e6e6 50%, #fefefe 100%);
  background-size: 400% 400%;
  background-position: 0 0;
  animation: skeleton-2 1.2s ease-in-out infinite;
}
@keyframes skeleton-2 {
  to {
    background-position: -135% 0;
  }
}
</style>
